What do the lungs sound like upon auscultation in a person with pneumonia?

Lung Sounds in Pneumonia

In pneumonia, the lungs most characteristically produce inspiratory crackles (heard in approximately 81% of cases), along with diminished breath sounds over affected areas due to consolidation. 1

Primary Auscultatory Findings

Crackles (Most Common)

• Inspiratory crackles are the hallmark finding, representing the sudden opening of collapsed alveoli and airways filled with inflammatory exudate 1
• These crackles typically occur in the late inspiratory phase and are focal over the affected lung region 2, 1
• The crackles progressively increase in pitch during inspiration, rising approximately 40 Hz from early to mid-inspiration and another 40 Hz from mid to late-inspiration 3
• In lateral decubitus positioning, persistent late inspiratory crackles in the dependent lung are highly suggestive of pneumonia 4

Diminished Breath Sounds

• Reduced air movement over consolidated areas produces diminished or decreased breath sounds in affected lung regions 1, 5
• This finding, combined with crackles, significantly increases the likelihood of pneumonia 1

Bronchial Breathing

• In cases with significant consolidation, bronchial breathing may be heard over the affected area, characterized by a higher ratio of expiratory to inspiratory sound intensity 6
• This represents transmission of central airway sounds through consolidated lung tissue 6

Additional Findings

Rhonchi

• May be present, though less specific than crackles 1
• The American Academy of Pediatrics includes rhonchi as a clinical finding suggestive of lower respiratory tract infection 1

Highly Specific But Less Common Findings

• Dull percussion note over the affected area is highly specific when present 5
• Pleural rub may be heard if pleural inflammation is present, also highly specific 5

Clinical Decision Algorithm

When crackles are present with:

• Fever ≥38°C, tachypnea (>25/min), and dyspnea → pneumonia is highly likely; proceed to chest radiography 2, 1
• Tachycardia (>100 bpm) and chest pain → strongly suggestive of pneumonia 2

When crackles are present without fever or dyspnea:

• Consider measuring C-reactive protein (CRP); CRP >30 mg/L strengthens pneumonia diagnosis 1

When auscultation is normal:

• Combined with normal vital signs, routine antibiotics are not recommended 1
• However, the absence of crackles does not completely exclude pneumonia, particularly in elderly or immunocompromised patients 1

Important Caveats

Limitations of Auscultation

• Requires specialized training to differentiate sounds accurately 2
• Needs a quiet examination environment, which may not be available in all settings 2, 1
• The World Health Organization guidelines for frontline workers do not include auscultation in diagnostic criteria due to these practical limitations 2, 1

Non-Specific Findings

• Wheezing, cough, prolonged expirations, or rhonchi alone do not significantly increase the likelihood of pneumonia 1
• Crackles can also be heard transiently in healthy individuals when placed in lateral decubitus positions (18.9% of controls), though these are transient rather than persistent 4
• In acute bronchitis, auscultation may be normal or show only diffuse bronchial rales, not focal crackles 2

Atypical Presentations

• Elderly patients may have absent or altered physical examination findings despite radiographic pneumonia 1
• Some patients may present with acute exacerbations rather than the typical gradual onset 2

Confirmation Required

Chest radiography remains essential to confirm pneumonia diagnosis when abnormal breath sounds and vital signs are present, as clinical findings alone are insufficient for definitive diagnosis 1, 5